An in silico study of the selective adsorption and separation of CO 2 from a flue gas mixture (CH 4 , CO 2 , N 2 ) by ZnLi 5 + clusters.

Due to the increasing concentration of CO 2 in the atmosphere and its negative effect on the environment, selective adsorption of CO 2 from flue gas has become significantly important. In this study, we have considered a Zn-doped lithium cluster, ZnLi 5 + cluster, featuring a planar pentacoordinate Zn centre, as a potential candidate for selective CO 2 capture and separation from a flue gas mixture (CH 4 , CO 2 , N 2 ). The binding energy calculation and non-covalent interaction study showed that CO 2 molecules bind relatively strongly as compared to N 2 and CH 4 molecules. The metal cluster can bind five CO 2 , five CH 4 , and four N 2 molecules with average binding energies of -9.2, -4.4, and -6.1 kcal mol -1 , respectively. Decomposition of the binding energy through symmetry-adapted perturbation theory analysis reveals that the electrostatic component plays a major role. The cationic cluster may be a promising candidate for selective CO 2 capture and can be used as a pollution-controlling agent. The calculated adsorption energy of H 2 S is quite closer to that of CO 2 , suggesting competitive adsorption between CO 2 and H 2 S. The adsorption energies of H 2 O and NH 3 are higher compared to CO 2 , indicating that these gases may be a potential threat to CO 2 capture.